Radio base station

ABSTRACT

A radio base station having a cabinet and a fan. The cabinet houses wireless communication equipment, and the fan cools the wireless communication equipment. The radio base station also includes at least one vent substantially perpendicular to air flow through the fan. This substantially perpendicularly arranged vent reduces atmospheric/ocean breezes from entering the radio base station and overheating the wireless communication equipment. The radio base station may also include at least one louvered vent having an open position and a closed position, the open position flowing air to or from the fan, and the closed position reducing the flow of air to or from the fan. The wireless communication equipment transmits frequencies between 806-960 MHz, between 1710-1885 MHz, or between 2500-2690 MHz.

NOTICE OF COPYRIGHT PROTECTION

A portion of the disclosure of this patent document and its figurescontain material subject to copyright protection. The copyright ownerhas no objection to the facsimile reproduction by anyone of the patentdocument or the patent disclosure, but otherwise reserves all copyrightswhatsoever.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally relates to wireless communications and, moreparticularly, to heating and cooling radio base stations.

2. Description of the Related Art

Wireless communication has experienced explosive growth. In just a fewyears cellular telephone usage has soared, and growth continues aswireless Internet access improves. This explosive growth hasrevolutionized data and voice communication, and manufacturers arecontinually striving to improve wireless equipment to meet the explosivegrowth.

Radio base stations are one example of continuously improving wirelessequipment. Radio base stations are self-contained enclosures that housetransmitters, receivers, and other wireless communication equipment.While radio base stations were originally designed for indoorinstallations, explosive growth has forced manufacturers to designoutdoor radio base stations. These outdoor radio base stations arelarge, so wireless service providers often seek installation sites onthe roofs of buildings. Tall urban buildings provide better transmissionand reception while hiding the often aesthetically-unpleasant radio basestation.

These outdoor radio base stations, however, are prone to overheating.The roofs of urban buildings are very hot in the summer and very cold inthe winter. If the wireless communication equipment is exposed totemperatures lying outside an operating range, the equipment may failfrom thermal stress. Some radio base stations have heaters and airconditioners to keep the wireless communication equipment within theoperating range. Even with air conditioning, however, light breezes candrastically affect the radio base stations. These breezes blow into theradio base station and frequently cause the wireless communicationequipment to fail from overheating. When the wireless communicationequipment fails, wireless service is interrupted. An interruption inservice irritates customers, disrupts daily business activities, andreduces revenue for the service provider.

FIG. 1 shows the prior art problem that causes radio base stations tothermally fail. FIG. 1 is a schematic drawing of a prior art radio basestation 10. The prior art radio base station 10 includes a cabinet 12that houses wireless communication equipment (not shown for simplicity).An electric fan 14 is shown through a cutaway portion 16 in the cabinet12. The fan 14 is a component of a heating, ventilating, and airconditioning (HVAC) system that cools the wireless communicationequipment (the complete HVAC system, for simplicity, is also not shown).The fan 14 is designed to exhaust air through one or more vents 18 in ahood 20. The problem, however, is that breezes blow through the vents 18and straight into the fan 14. These breezes, as explained below,eventually cause the wireless communication equipment to fail.

Breezes reverse spin the fan 14. Breezes flow through the hood 20 andinto the fan 14. If the fan 14 is not receiving electricity, the breezesspin the fan 14 in reverse. As the fan 14 free-spins in reverse, the fan14 draws in warm air. When the HVAC system detects rising temperaturesin the prior art radio base station 10, an air conditioner turns on andsends alternating current to the fan 14. The fan 14, however, is alreadyspinning in reverse due to the breeze. When alternating current isapplied to the reverse-spinning fan 14, the fan 14 does not changedirection—fan 14 actually speeds up and continues to reverse spin. Thefan 14 has a “squirrel-cage” design which permits the fan 14 to run ineither direction. Although the air conditioner is operating, the fan 14is spinning in reverse and drawing hot air into the air conditioner. Theair conditioner quickly becomes ineffective, and the wirelesscommunication equipment exceeds the maximum operating temperature. Theprior art radio base station 10 then fails from thermal stress.

This prior art design creates another problem. Ambient air iscontaminated with dust his and dirt. The direct flow path from the vents18 to the fan 14 carries dust and dirt into the air conditioner. The fan14 clogs and the cooling efficiency of the air conditioner reduces. Evenif the HVAC system is filtered, the filter also clogs and obstructs airflow into the HVAC system. The direct flow path from the vents 18 to thefan 14 allows dust and dirt to cascade toward thermal stress failures.

There is, accordingly, a need for a radio base station that has areduced rate of thermal stress failures, a radio base station that isless susceptible to dust and dirt infiltration, and, yet, a radio basestation design that can resolve the prior art problems without extensivetooling or revisions.

BRIEF SUMMARY OF THE INVENTION

The aforementioned problems are minimized by a radio base station havingan indirect air flow path. The design of this radio base stationeliminates the direct air flow path from the vents to the fan. Thisindirect flow path substantially reduces the tendency of breezes toreverse-spin the fan. The indirect flow path also helps reduceinfiltration of dust and dirt. The HVAC system is more efficient, sothermal stress failures are reduced. The indirect flow path is alsoquickly and inexpensively implemented in both new and existing radiobase stations. The indirect flow path of the present invention reducesfailures, improves customer satisfaction and service, and increasesrevenues for service providers.

The indirect flow path is achieved by relocating the vents. The presentinvention relocates the vents at approximately right angles to air flowthrough the fan. Regardless of from what direction breezes blow, thebreezes will not encounter a direct path to the fan. The vents arearranged approximately perpendicular to air flow through the fan and,thus, an indirect path is achieved. This approximately perpendiculararrangement reduces reverse free-spinning in the fan.

The indirect path is also achieved by other vent and fan arrangements.The present invention contemplates any arrangement that reduces air fromflowing directly into the fan. Whether the vents are arranged at (30degrees (30°), forty five degrees (45°), sixty degrees (60°), eightydegrees (80°), or any arrangement in between, the air flows indirectlyto the fan. This indirect flow path reduces failures in the wirelesscommunication equipment.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

These and other features, aspects, and advantages of the mobiletransmitter locator are better understood when the following DetailedDescription of the Invention is read with reference to the accompanyingdrawings, wherein:

FIG. 1 is a schematic drawing of a prior art radio base station;

FIG. 2 is a schematic drawing showing one concept of the presentinvention;

FIG. 3 is a front view of a radio base station incorporating the presentinvention;

FIG. 4 is a sectional view of the radio base station 24 shown in FIG. 3;

FIGS. 5A, 5B, and 5C are, respectively, left side, front, and right sideviews of the hood 38 shown in FIGS. 3 and 4;

FIG. 6 is a rear view of the hood shown in FIGS. 4 and 5;

FIG. 7 is a sectional view of the hood taken along Line 7—7 of FIG. 6;

FIGS. 8 and 9 show an alternative embodiment of the present invention;and

FIG. 10 shows still another alternative embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is a radio base station less susceptible tooverheating by ambient winds. The radio base station includes a cabinethousing wireless communication equipment. A fan is used to cool thewireless communication equipment. One or more vents are arrangedsubstantially perpendicular to air flowing through the fan. Thesesubstantially perpendicular vents reduce atmospheric/ocean breezes fromentering the radio base station and from overheating the wirelesscommunication equipment. The vents may be louvered to further reduceoverheating. The wireless communication equipment transmits frequenciesbetween 806-960 MHz, between 1710-1885 MHz, or between 2500-2690 MHz.

An alternative radio base station is also disclosed. This alternativehas a cabinet housing wireless communication equipment, and a fancooling the wireless communication equipment. The radio base stationincludes at least one louvered vent having an open position and a closedposition, the open position flowing air to or from the fan, and theclosed position reducing the flow of air to or from the fan.

FIG. 2 is a schematic drawing of the indirect flow path. The presentinvention exhausts air through a side vent 22. The side vent 22 is atapproximately right angles to air flow through the fan 14. The fan 14can still exhaust air, but breezes cannot flow directly into the fan 14.The vent 22 is approximately perpendicular to air flow through the fan14 and, thus, the ability of the fan 14 to reverse free-spin issubstantially reduced. The indirect flow path, of course, contemplatesany arrangement that reduces air from flowing directly into the fan 14.Whether the vent 22 is arranged at thirty degrees (30°), forty fivedegrees (45°), sixty degrees (60°), eighty degrees (80°), or anyarrangement in between, the air flows indirectly to the fan 14. Thisindirect flow path reduces thermal failures in the wirelesscommunication equipment.

FIG. 3 is a front view of a radio base station 24 incorporating thepresent invention. The radio base station 24 shown is the Ericsson® RBS884 family of Time Division Multiple Access products (Ericsson® is aregistered trademark of Telefonaktiebolaget LM Ericssonhouses,Telefonvägen 30, 12625 Stockholm, Sweden, phone: +46 8 719 00 00,www.ericsson.com). Those skilled in the art of wireless communicationunderstand that the Ericsson® 884 family is only a representativeexample of radio base stations, and that the present invention isequally applicable to other radio base station designs and other radiobase station manufacturers.

Those skilled in the art of wireless communication also recognize thepresent invention is applicable to all wireless communication products,methods, and frequencies. The present invention is applicable to radiobase stations utilizing code-division multiple access (CDMA)technologies, time-division multiple access (TDMA) technologies, and theglobal system for mobile communications (GSM) technology. The presentinvention is also applicable to radio base stations transmitting andreceiving all frequencies in the electromagnetic spectrum and iscompatible with the June, 2000 World Radiocommunication Conferenceagreement on third-generation cellular telephony (806-960 MHz, 1710-1885MHz, and 2500-2690 MHz). See William Sweet, Cell phones answerInternet's call, IEEE SPECTRUM, Aug. 2000, at 43. Radio base stationstransmitting and receiving radio frequencies, such as the industrial,scientific, and medical (ISM) band of the electromagnetic spectrum (2.4GHZ-2.5 GHz) (e.g, “Bluetooth”), are also applicable.

The radio base station 24 has a cabinet 26, with the cabinet 26including a left door 28 and a right door 30. The left door 28 and theright door 30 have corresponding door latches 32 and 34. The radio basestation 24 may include a high-voltage electrical service box 36 forreceiving electrical power. As those skilled in the art of wirelesscommunication understand, the cabinet 26 houses wireless electronicequipment for providing wireless service. The radio base station 24 mayalso include an HVAC hood 38 and one or more vents 40. The one or morevents 40 flow air to heat and to cool the wireless electronic equipmenthoused within the radio base station 24.

FIG. 4 is a sectional view of the radio base station 24 shown in FIG. 3.The cabinet 26 is sectioned such that the HVAC hood 38 is shownunobstructed by the high-voltage electrical service box (shown asreference numeral 36 in FIG. 3). The sectioned cabinet 26 exposesrack-mounted wireless communication equipment 42 and a Heating,Ventilating, and Air Conditioning (HVAC) system 44. The HVAC system 44may have four (4) major components: a compressor 46, a first heatexchanger 48, a second heat exchanger 50, and a squirrel cage fan 52. Asthose skilled in the art have long understood, the HVAC system 44operates to heat and to cool an interior region 54 of the cabinet 26.The HVAC system 44 has a cooling mode where heat is removed from theinterior region 54. See KENNETH WARK, THERMODYNAMICS 716-14 (1983). TheHVAC system 44 also has a heating mode where heat is added to theinterior region 54. See id Because the operation of the HVAC system 44is well understood, the HVAC system 44 is simply shown as a blockdiagram.

The fan 52 flows air to and from the HVAC system 44. The fan 52, forexample, forces air through a duct 56, through a passage 58, and out thevent 40. The vent 40, however, is substantially perpendicularly arrangedto the flow of air through the fan 52. This substantially perpendiculararrangement reduces atmospheric/ocean breezes from entering the vent 40and free spinning the fan 52 in reverse. As those skilled in the artunderstand, if electrical current is applied to the reverse-spinningsquirrel cage fan 52, magnetic fields within the fan 52 align and thefan 52 continues to reverse-spin. The substantially perpendiculararrangement of the side vent 42 thus reduces breezes from entering thevent 40, flowing to the passage 58 and entering the duct 56, and thenfree-spinning the fan 52. The substantially perpendicular arrangement ofthe vent 40 reduces untreated air from overheating the interior region54. The substantially perpendicular arrangement of the vent 40 thusreduces fluctuations in the environmental operating range of theelectronic equipment 42 housed in the cabinet 26.

As FIG. 4 shows, the radio base station 24 may have multiple side ventsand passages. A second vent 60 and a third vent 62 are shown. As thoseskilled in the art recognize, each vent 40, 60, and 62 may communicatewith the passage 58 to flow air to and from the HVAC system 44. Eachvent 40, 60, and 62, alternatively, may communicate with multiplepassages or even dedicated, ducted passages. The second side vent 60,for example, may only communicate with a second passage 64. The thirdside vent 62, likewise, may communicate only with a third passage 66.Those skilled in the art recognize the flow of air may be designed tosuit any configuration of the HVAC system 44 necessary to heat and coolthe interior region 54.

FIGS. 5A, 5B, and 5C are, respectively, left side, front, and right sideviews of the hood 38 shown in FIGS. 3 and 4. The vents 40, 60, and 62are arranged in a right side panel 68 and allow air to flow to and fromthe HVAC system (shown as reference numeral 44 in FIG. 4). Additionalvents 70, 72, and 74 in a left side panel 76 may also allow air to flowto and from the HVAC system. The right side panel 68 and the left sidepanel 76 outwardly extend from a back panel 78 to a front panel 80. Atop panel 82 and a bottom panel 84 also outwardly extend from the backpanel 78 to the front panel 80. The right side panel 68, left side panel76, back panel 78, front panel 80, top panel 82, and bottom panel 84form an enclosure 86. The vents 40, 60, 62, 70, 72, and 74 allow air toflow to and from the enclosure 86. The hood 38 further includes aplurality of openings 88 for attaching the hood 38 to the cabinet (shownas reference numeral 26 in FIGS. 3 and 4). The hood 38 may also includea nozzle 90 through which condensation flows from the HVAC system.

FIG. 6 is a rear view of the hood 38. The back panel 78 includes thepassage 58. The passage 58 communicates with the HVAC system (shown asreference numeral 44 in FIG. 4) to flow air between the HVAC system andthe ambient environment. The back panel 78 may also include the secondpassage 64 and the third passage 66 to further flow air between the HVACsystem and the ambient environment. The plurality of openings 88 arealso shown.

FIG. 7 is a sectional view taken along Line 7—7 of FIG. 6. Thissectional view shows the hood 38 may include one or more partitions tochannel air flow within the enclosure 86. As those skilled in the artrecognize, an upper partition 92 only permits air flow communicationbetween the passage 58 and the vent 70 (and, if desired, the oppositevent shown as reference numeral 40 in FIGS. 3, 4, and 5C). A lowerpartition 94, likewise, may further channel air flow communicationbetween the second passage 64 and the vent 72 (and, if desired, theopposite vent shown as reference numeral 60 in FIG. 5C). The lowerpartition 94 would also channel air flow communication between the thirdpassage 66 and the vent 74 (and, if desired, the opposite vent shown asreference numeral 62 in FIG. 5C). HVAC systems are well understood, andthose skilled in the art recognize more or less partitions may be usedto channel air flow as desired.

FIGS. 8 and 9 show an alternative embodiment of the hood 38. Thisalternative embodiment utilizes hinged louvers to reduce atmospheric andocean breezes from free spinning the fan (shown as reference numeral 52in FIG. 4). The vent 40, for example, includes an array 96 of louvers.Each louver 98 in the array 96 of louvers is hinged to open and allowair flow in one direction. Each louver 98, however, closes when airflows in an opposite direction. FIG. 8 shows the array 96 of louvers inan open position to permit air to flow from the fan and out through thevent 40. If atmospheric or ocean breezes impinge the array 96 oflouvers, each louver 98 pivots to a closed position. FIG. 9 shows thearray 96 of louvers in the closed position. While FIGS. 8 and 9 show theother vents 60, 62, 70, 72, and 74 with corresponding arrays 100, 102,104, 106, and 108 of louvers, those skilled in the art understand theHVAC hood 38 may be designed with some vents having arrays of louversand other vents not having arrays of louvers.

FIG. 10 shows still another alternative embodiment of the presentinvention. This alternative embodiment similarly utilizes hinged louversto reduce atmospheric and ocean breezes from free spinning the fan(shown as reference numeral 52 in FIG. 4). The right side panel 68 andthe left side panel 76, however, are shown without vents. The frontpanel 80 in this embodiment includes at least one louvered front vent110. FIG. 10 shows an array 112 of louvers in an open position to permitair to flow from the fan and out through the louvered front vent 110. Ifatmospheric or ocean winds impinge the array 112 of louvers, each louver114, like those shown in FIG. 9, will close and prevent wind fromentering the louvered front vent 110. While FIG. 10 also shows a secondlouvered front vent 116 and a third louvered front vent 118, thoseskilled in the art understand the HVAC hood 38 may be designed with anycombination of side vents, louvered side vents, and louvered frontvents.

The present invention is equally applicable to radio base stationswithout an HVAC system. The present invention is applicable to naturalconvention system and a forced-fan system. A natural convention system,for example, would also utilize the perpendicularly arranged vents andthe louvered vents described in this patent. A natural conventionsystem, as those skilled in the art understand, heats the wirelesscommunication equipment by solar gain or electrical heat loss. Aforced-fan system also utilizes a fan to flow ambient, filtered, orisolated air to the wireless communication equipment.

While this invention has been described with respect to variousfeatures, aspects, and embodiments, those skilled and unskilled in theart will recognize the invention is not so limited. Other variations,modifications, and alternative embodiments may be made without departingfrom the spirit and scope of the following claims.

What is claimed is:
 1. A radio base station, comprising: a cabinethousing wireless communication equipment; a fan cooling the wirelesscommunication equipment; and a vent substantially perpendicular to airflow through the fan, the vent including an array of hinged louvers,each of the hinged louvers being hinged to open or close based on adirection of air flow through the fan.
 2. A radio base station accordingto claim 1, wherein the radio base station includes more than one ventsubstantially perpendicular to air flow through the fan.
 3. A radio basestation according to claim 1, wherein each of the hinged louvers ishinged to open for flowing air to or from the fan in one direction, andis hinged to close for reducing the flow of air to or from the fan whenair flows in an opposite direction.
 4. A radio base station according toclaim 1, further including a hood containing the vent.
 5. A radio basestation according to claim 1, wherein the fan is a component of aheating, ventilating, and air conditioning system.
 6. A radio basestation according to claim 1, wherein the wireless communicationequipment transmits frequencies between 806-960 MHz.
 7. A radio basestation according to claim 1, wherein the wireless communicationequipment transmits frequencies between 1710-1855 MHz.
 8. A radio basestation according to claim 1, wherein the wireless communicationequipment transmits frequencies between 2500-2690 MHz.
 9. A radio basestation according to claim 1, wherein the wireless communicationequipment transmits frequencies between 2.4 GHz-2.5 GHz.
 10. A radiobase station, comprising: a cabinet housing wireless communicationequipment; a fan cooling the wireless communication equipment; and atleast one louvered vent, wherein the vent includes an array of hingedlouvers, each of the louvers is hinged to open for allowing air flow inone direction in the fan, and each of the louvers is hinged to close forpreventing atmospheric and ocean breezes from free spinning the fan,when air flows in an opposite direction in the fan.
 11. A radio basestation according to claim 10, wherein the fan is a component of aheating, ventilating, and air conditioning system.
 12. A radio basestation according to claim 10, wherein the wireless communicationequipment transmits frequencies between 806-960 MHz.
 13. A radio basestation according to claim 10, wherein the wireless communicationequipment transmits frequencies between 1710-1855 MHz.
 14. A radio basestation according to claim 10, wherein the wireless communicationequipment transmits frequencies between 2500-2690 MHz.
 15. A radio basestation according to claim 10, wherein the wireless communicationequipment transmits frequencies between 2.4 GHz-2.5 GHz.
 16. A radiobase station, comprising: a cabinet housing wireless communicationequipment; a fan cooling the wireless communication equipment; and ahood having a vent substantially perpendicular to air flow through thefan, the vent including an array of hinged louvers, each of the hingedlouvers being hinged to open or close based on a direction of air flowthrough the fan.
 17. A radio base station according to claim 16, whereinthe hood includes more than one vent substantially perpendicular to airflow through the fan.
 18. A radio base station according to claim 16,wherein the wireless communication equipment transmits frequenciesselected from the group consisting of 806-960 MHz, 1710-1855 MHz,2500-2690 MHz, and 2.4-2.5 GHz.
 19. A radio base station according toclaim 16, wherein each of the hinged louvers is hinged to open forflowing air to or form the fan in one direction, and is hinged to closefor reducing the flow of air to or from the fan when air flows in thefan in an opposite direction.